1. Technical Field
The present invention relates to a paper cassette to be loaded in an image recording system, such as a copier, facsimile, printer or the like. More specifically, the present invention relates to a so-called universal type of paper cassette simple in construction and capable of storing papers of different sizes and selectively feeding the stored papers into the image recording system.
2. Background Art
Generally, there are two types of paper cassettes used in an image recording system capable of recording papers of different sizes. The traditional type of paper cassette is capable of storing and feeding papers of a predetermined size. Consequently, if the image recording system were to record papers of different sizes, a plurality of paper cassettes, each being used for one paper size, is required so that papers can be fed selectively. However, the image recording system in which papers with multiple sizes are fed requires a corresponding plurality of paper feeders and becomes complicated, costly and large in size. In order to avoid these problems, a modem type of paper cassette referred to as a so-called universal paper cassette has been introduced, and is capable of storing and selectively feeding papers of different sizes, e.g., A4 size, letter size and legal size etc.
Typically, the universal paper cassette has a cassette body capable of containing papers of the largest size, and a pair of position regulation members movably installed in the cassette body to accommodate papers of different sizes. For example, in U.S. Pat. No. 4,343,461 for Paper Feeding Cassette issued to Tomimori et at., and U.S. Pat. No. 5,297,787 for Sheet Cassette issued to Shirai, the universal paper cassette includes a bottom plate movable in the paper-feeding direction to accommodate papers of different lengths and a single or a pair of side plates movable in the direction perpendicular to the paper-feeding direction so as to accommodate papers of different widths. The side plates could be adjusted as shown in U.S. Pat. No. 4,907,792 for Sheet Guide Adjusting Apparatus issued to Washiashi et al., Japanese Utility Model Publication No. 6-64759 for Paper Feed Guide Device For Document Or The Like issued to Kiuchi, Japanese Utility Model Publication No. 2-100930 for Universal Blank Form Cassette issued to Sakamoto by a gear mechanism i.e., a cam member comprised of a pinion and a cam follower for enabling the side plates to move in a reciprocal manner to accommodate papers of different widths in the cassette.
Alternatively, the single side plate could be adjusted in conjunction with the bottom plate by a gear mechanism to accommodate papers of different widths and lengths as shown in U.S. Pat. No. 4,786,042 for Adjustable Size Sensing Sheet Cassette issued to Stemmle and Japanese Utility Model Publication No. 3-166129 for Universal Cassette issued to Ito. The bottom plate could be adjusted manually either by a single lever as disclosed in Japanese Utility Model Publication No. 63-185730 for Paper Feeding Cassette issued to Yoshida, or alternatively by a plurality of paper discriminating levers as disclosed in Japanese Utility Model Publication No. 6-24586 and No. 6-32489 for Universal Paper Feeding Cassette issued to Ui. Ordinarily, these conventional paper cassettes however do not provide simple visual display of different sizes of papers stored in the cassette body to be fed into the image recording system when the paper cassettes are loaded into the image recording system.
Other universal paper cassettes such as those shown in U.S. Pat. No. 5,333,852 for Auto Paper Size Sensing Mechanism For An Adjustable Cassette issued to Milillo et al. are more sophisticated in that an automatic paper size sensing mechanism including an actuator arm attached to side plates having a plurality of switch actuators for selectively actuating a plurality of switches on the main body which respectively represent different paper sizes so as to allow a controller to interpret the length or width dimension of the paper in the cassette. Consequently, while Milillo '852 provides a visual display of papers of different sizes, he does so electronically.
U.S. Pat. No. 4,697,803 for Sheet Member Feeding Cassette issued to Kan et al., on the other hand, discloses an indicator panel comprising a plurality of characters and symbols formed on a side wall of a cassette to provide a visual display of the different size paper in the cassette via a window. Similarly, Japanese Utility Model Publication No. 57-131642 for Paper Supply Device issued to Hayakawa also provides a paper size display portion formed on a cassette body along with a lever connected to paper holders via a slider for enabling a user to adjust the paper holders to accommodate papers of different sizes manually. However, the internal working mechanism of Kan '803 and Hayakawa '642 is relatively complicated.